Read the pH: below 7.35 is acidosis, above 7.45 alkalosis.
Find the value that explains it: PaCO₂ moving opposite to the pH is respiratory, HCO₃⁻ moving with the pH is metabolic.
Look at the other value: normal means uncompensated, abnormal in the compensating direction means partial compensation, and a normal pH with both abnormal means full compensation.
In a metabolic acidosis, compare PaCO₂ with Winter’s formula, 1.5·HCO₃⁻ + 8 ± 2, and calculate the anion gap Na⁺ − (Cl⁻ + HCO₃⁻).
Check a high anion gap with the delta ratio and, when albumin is low, with the corrected gap.
Nursing math & unit conversions
Metric steps
1 kg = 1000 g, 1 g = 1000 mg, 1 mg = 1000 mcg, 1 L = 1000 mL
Weight and length
1 kg = 2.2 lb, 1 lb = 16 oz, 1 in = 2.54 cm, 1 ft = 12 in
Household measures
1 tsp = 5 mL, 1 tbsp = 15 mL, 1 fl oz = 30 mL, 1 cup = 8 fl oz = 240 mL
Write the given quantity with its unit and the unit you want.
Pick the equivalent: 1000 between kg, g, mg and mcg or L and mL; 1 kg = 2.2 lb; 1 tsp = 5 mL, 1 tbsp = 15 mL, 1 fl oz = 30 mL, 1 cup = 240 mL.
Write it as a fraction so that the unwanted unit cancels; for a rate, use one fraction per unit that changes.
Check the direction: a smaller unit gives a bigger number.
Round only the final answer, to the precision the question names.
2Practice problems
1.Clinical assessment scoresMedium
Practice exercise (made-up values, not clinical guidance). Use the NEWS2 chart (SpO₂ scale 1) for these observations: respiration rate 20/min, SpO₂ 95% on supplemental oxygen, blood pressure 136/82 mmHg, pulse 132/min, alert, temperature 37.0 °C. What is the NEWS2 total score?
RR 20SpO₂ 95%O₂SBP 136HR 132AT 37.0 °C
NEWS2 =
2.Clinical assessment scoresHard
Practice exercise (made-up values, not clinical guidance). At 1 minute after birth, a practice newborn has blue or pale skin all over, a heart rate of 60/min, a grimace when stimulated, limp limbs with no muscle tone and slow, irregular breathing with a weak cry. Score the APGAR and click how the score is interpreted.
1reassuring
2moderately abnormal
3low
3.Arterial blood gas interpretationMedium
A practice gas shows PaCO₂ 61 mmHg (8.1 kPa). Use the rule that in chronic respiratory acidosis HCO₃⁻ rises by 3.5 mmol/L for every 10 mmHg that PaCO₂ is above 40, starting from HCO₃⁻ 24 mmol/L, to find the expected HCO₃⁻.
A practice gas shows a respiratory acidosis: pH 7.31, PaCO₂ 79 mmHg (10.5 kPa), HCO₃⁻ 38 mmol/L. Use the rules ‘HCO₃⁻ rises 1 mmol/L per 10 mmHg (acute) or 3.5 mmol/L per 10 mmHg (chronic)’ to classify it. Click your answer.
pH 7.31PaCO₂ 79 mmHg (10.5 kPa)HCO₃⁻ 38 mmol/L
1acute
2chronic
3acute on chronic
5.Nursing fundamentalsMedium
Before fitting anti-embolism stockings, what should the nurse do?
AMeasure the legs to get the right size and check for arterial disease
BFit the tightest size available so the stockings give the best effect
CChoose a size by looking at the patient's shoe size and weight
DFit them over existing bandages or wounds
6.Nursing fundamentalsHard
A patient has a platelet count of 40 × 10⁹/L (40,000/mm³). Which nursing measure is appropriate?
AGive aspirin for any headaches
BEncourage contact sports to raise the count
CUse a firm toothbrush and floss hard to keep the gums healthy
DUse a soft toothbrush and avoid IM injections where possible
7.Nursing math & unit conversionsMedium
Practice exercise (made-up values, not clinical guidance). A dose is charted at 9:25 AM. Which entry is the same time on the 24-hour clock? Click it.
9:25 AM
109:25
221:25
310:25
408:25
8.Nursing math & unit conversionsHard
Practice exercise (made-up values, not clinical guidance). An order reads 8 mcg/kg/min for a patient who weighs 73 kg. Express the dose rate D in mg/h. Round to two decimal places.
8 mcg/kg/min73 kg
D = mg/h
3Solutions
1.Clinical assessment scores
Answer: NEWS2 = 6
NEWS2 (National Early Warning Score 2, Royal College of Physicians 2017): score each of the seven parameters with the chart (respiration rate, SpO₂ on scale 1, air or supplemental oxygen, systolic blood pressure, pulse, consciousness on the ACVPU scale and temperature) and add the scores. Clinical risk: 0–4 low; a score of 3 in any single parameter low–medium; 5–6 medium; 7 or more high. A total of 5 or more needs an urgent response.
Score each parameter
RR 20/min → 0
SpO₂ 95% → 1
on oxygen → 2
SBP 136 mmHg → 0
HR 132/min → 3
alert (A) → 0
T 37.0 °C → 0
Add
NEWS2 = 0 + 1 + 2 + 0 + 3 + 0 + 0 = 6
Answer
NEWS2 = 6
2.Clinical assessment scores
Answer: low
APGAR score: five signs, each scored 0, 1 or 2, checked at 1 and 5 minutes after birth. Appearance (colour): blue or pale 0, pink body with blue extremities 1, pink all over 2. Pulse: absent 0, below 100/min 1, 100/min or more 2. Grimace (reflex irritability): none 0, grimace 1, cry, cough or sneeze 2. Activity (tone): limp 0, some flexion 1, active movement 2. Respiration: absent 0, slow or irregular with a weak cry 1, good with a strong cry 2. A total of 7–10 is reassuring, 4–6 moderately abnormal and 0–3 low.
Score each sign
Appearance: blue or pale skin all over → 0
Pulse: 60/min → 1
Grimace: a grimace when stimulated → 1
Activity: limp limbs with no muscle tone → 0
Respiration: slow, irregular breathing with a weak cry → 1
Add
APGAR = 0 + 1 + 1 + 0 + 1 = 3
Interpretation
3 → low
Answer
low
3.Arterial blood gas interpretation
Answer: HCO₃⁻ = 31.35 mmol/L
Expected compensation: in metabolic acidosis Winter’s formula predicts PaCO₂ = 1.5·HCO₃⁻ + 8 ± 2 mmHg; a measured value above that range points to an additional respiratory acidosis, below it to an additional respiratory alkalosis. The anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), normally about 8–12 mmol/L, separates high-gap from normal-gap metabolic acidosis; low albumin hides a high gap (add 2.5 per g/dL that albumin is below 4.0). The delta ratio (AG − 12)/(24 − HCO₃⁻) between about 0.8 and 2 fits a pure high-gap acidosis (some texts use 1 instead of 0.8), below that an added normal-gap acidosis, and above 2 an added metabolic alkalosis.
Change in PaCO₂
|61 − 40| = 21 mmHg → 2.1 × 10 mmHg
Expected HCO₃⁻
HCO₃⁻ = 24 + 3.5·2.1 = 31.35 mmol/L
Answer
HCO₃⁻ = 31.35 mmol/L
4.Arterial blood gas interpretation
Answer: chronic
Expected compensation: in metabolic acidosis Winter’s formula predicts PaCO₂ = 1.5·HCO₃⁻ + 8 ± 2 mmHg; a measured value above that range points to an additional respiratory acidosis, below it to an additional respiratory alkalosis. The anion gap AG = Na⁺ − (Cl⁻ + HCO₃⁻), normally about 8–12 mmol/L, separates high-gap from normal-gap metabolic acidosis; low albumin hides a high gap (add 2.5 per g/dL that albumin is below 4.0). The delta ratio (AG − 12)/(24 − HCO₃⁻) between about 0.8 and 2 fits a pure high-gap acidosis (some texts use 1 instead of 0.8), below that an added normal-gap acidosis, and above 2 an added metabolic alkalosis.
Expected HCO₃⁻
acute: 24 + 1·3.9 = 27.9 mmol/L
chronic: 24 + 3.5·3.9 = 37.65 mmol/L
Compare
measured: 38 mmol/L → chronic
Answer
chronic
5.Nursing fundamentals
Answer: A · Measure the legs to get the right size and check for arterial disease
Why this is the answer
Wrong-sized stockings can cause skin damage or a tourniquet effect. They are not used in significant peripheral arterial disease, and the skin is checked daily.
Answer
A · Measure the legs to get the right size and check for arterial disease
6.Nursing fundamentals
Answer: D · Use a soft toothbrush and avoid IM injections where possible
Why this is the answer
A low platelet count raises the risk of bleeding. Bleeding precautions include soft toothbrushes, electric razors, avoiding IM injections and avoiding aspirin and NSAIDs.
Answer
D · Use a soft toothbrush and avoid IM injections where possible
7.Nursing math & unit conversions
Answer: 09:25
24-hour clock: from 1 PM onwards add 12 to the hour (3:45 PM = 15:45). Midnight to 12:59 AM is 00:00–00:59, and 12:00–12:59 PM stays 12:00–12:59. Going back, subtract 12 from hours 13–23 and add PM; hours 00 become 12 AM. Count time across midnight in two parts: up to 24:00 (00:00), then from 00:00 on.
Convert the hour
9 AM → 09
Answer
09:25
Answer
09:25
8.Nursing math & unit conversions
Answer: D = 35.04 mg/h
Dimensional analysis: write the given quantity, then multiply by conversion factors written as fractions (for example 60 min/1 h or 1 mg/1000 mcg) so that each unwanted unit appears once on top and once underneath and cancels. When only the wanted unit is left, calculate. Use the equivalents the question gives and round only the final answer.
Set up the chain
D = 8 mcg/kg/min × 73 kg × (60 min/1 h) × (1 mg/1000 mcg)